/*
 * Copyright 1999-2018 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.csp.sentinel.transport.init;

import com.alibaba.csp.sentinel.command.CommandCenterProvider;
import com.alibaba.csp.sentinel.init.InitFunc;
import com.alibaba.csp.sentinel.init.InitOrder;
import com.alibaba.csp.sentinel.log.RecordLog;
import com.alibaba.csp.sentinel.transport.CommandCenter;

/**
 * @author Eric Zhao
 */
@InitOrder(-1)
public class CommandCenterInitFunc implements InitFunc {

    @Override
    public void init() throws Exception {
        //这里得到一个CommandCenter的实现类，这里也是通过jdk的spi去加载的
        //这里的spi找的是所有实现了com.alibaba.csp.sentinel.transport.CommandCenter的实现了
        //sentinel这里有两个实现
        //com.alibaba.csp.sentinel.transport.command.NettyHttpCommandCenter:这个是在sentinel-transport-netty-http
        //com.alibaba.csp.sentinel.transport.command.SimpleHttpCommandCenter：这个是在sentinel-transport-simple-http
        //simple-http使用的是bio，而netty肯定是nio，但是一般只用于和服务端进行规则的发布，一般使用simple-http也够了，没必要使用netty
        //所以这里就使用simple-http来分析下
        CommandCenter commandCenter = CommandCenterProvider.getCommandCenter();

        if (commandCenter == null) {
            RecordLog.warn("[CommandCenterInitFunc] Cannot resolve CommandCenter");
            return;
        }

        //commandCenter启动之前的一些操作，将所有的规则处理器的handler全部通过spi找到并且注册到一个map缓存中，key就是服务端发过来的操作，比如setRules
        commandCenter.beforeStart();
        //这里就是启动一个bio的线程来监听服务端发过来的请求，比如发布配置setRules
        commandCenter.start();
        RecordLog.info("[CommandCenterInit] Starting command center: "
                + commandCenter.getClass().getCanonicalName());
    }
}
